Abstract Body: Introduction:
Following the results of the WAKE-UP trial, the AHA and Japanese guidelines were revised in 2019 to recommend IV rt-PA for ischemic stroke patients who have unclear time of onset >4.5 hours from last known well, when MRI DWI-FLAIR mismatch is identified. Here, we investigated the actual implementation rate, efficacy, and safety of IV rt-PA in patients with unclear onset time ischemic stroke in an area with extremely high MRI prevalence.
Methods:
Using data from the K-NET Registry, a multi-center stroke registry in Kanagawa Japan, we investigated 2,021 patients who underwent IV rt-PA between January 2018 and December 2021. The patients included were divided into two groups: those with unclear onset time and >4.5 hours from last known well (UO) and those with clear onset time (CO), and their clinical backgrounds, treatment outcomes, and complications were compared.
Results:
The UO group consisted of 88 patients, which accounted for 4.4% of the included patients, while the CO group 1,933 patients. The UO group patients were significantly older (median age 81 vs 77 years, p<0.001). However, there were no significant differences in comorbidities (HT/DM/HL/af), pre-stroke mRS, NIHSS at admission, or stroke subtype. The door-to-needle time (DTN) was significantly longer in the UO group (60.5 minutes vs 53 minutes, p<0.01). Mechanical thrombectomy was performed in 62% of patients in both groups, with similar successful reperfusion (TICI 2b/3) rates (89.1% vs 92.0%). The rate of symptomatic intracerebral hemorrhage (sICH) was comparable between the groups (2.3% vs 2.6%). The rate of favorable outcome (mRS 0-1 at 3 months) was significantly lower in the UO group (28.4% vs 39.8%, p<0.05), though there was no difference in mortality between the groups (mRS 6 at 3 months) (6.8% vs 6.9%).
Conclusions:
Unlike previous reports, the rate of favorable outcome was lower in the UO group in this study. This study also showed that UO group patients were significantly older and had a significantly longer DTN; age bias, in addition to the additional time required for ischemia evaluation, may be responsible for the difference in outcomes. The similar rates of mechanical thrombectomy (including its success rate) and sICH complications may suggest that IV rt-PA itself worked well in the UO group.